Re: MNG/JNG specification updates

On Sat, Oct 10, 2015 at 8:47 PM, Adeluc <png-8CwYj0sA/[email protected]> wrote:

>
>
>
> If you decide that JNG also support stereoscopic image, to help you decide
> if the “_JPSJPS_” APP3 descriptor should be supported or if only the sTER
> chunk is enough, I suggest you to ask yourself what is a JNG file.  Is it a
> JPG file with an alpha channel?  Or is it a PNG file with a lossy but
> highly compression?
>
> My opinion is that if you think of JNG as a PNG file, you should simply
> ignore the complicated “_JPSJPS_” APP3 descriptor and simply support the
> sTER chunk.
>

I think so.

The current APG (0.94.10) draft allows the FRME chunk to contain a
"stereo_mode" byte:

   Stereo mode: 1 byte (unsigned integer)
                 0: unknown
                 1: none
                 2: both, left-right
                 3: both, right-left
                 4: alternating left,right frames
                 5: alternating right,left frames

The stereo_mode field can be supplied if the frames contain
stereo pairs. If stereo_mode is 1, the frames are not stereo.  If it
is 2 or 3, each frame contains a stereo pair. The mode should be consistent
with the embedded <span class="cn">sTER</chunk> in the PNG or JNG object,
if one is present.  If it is 4 or 5, frames following the
<span class="cn">FRME</span> chunk are in pairs of frames, either
in left-right order or right-left order.  If stereo_mode is omitted,
the existing stereo_mode is not changed. The default stereo_mode, when
it has not been defined on the current or a prior <span
class="cn">FRME</span>
chunk, is 0 ("unknown").

Glenn

------------------------------------------------------------------------------

_______________________________________________
png-mng-misc mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/png-mng-misc